One of the drawbacks of present-day ten-speed bicycles is the inability to mount accessories on the bicycle in a convenient, easy manner. This drawback is overcome by the present invention by the provision of a novel handlebar assembly, including a support bar which is easily and quickly attached to the normal handlebars of a ten-speed bicycle in a quick, efficient manner and which is also adjustable to accommodate different spacings between the hand grips of the handlebars and upon which may be easily and readily mounted a variety of bicycle accessories.